VNAV descent post Hot-Fix

[dazz 69]

After installing the hot fix I noticed that my 738 (no winglets) can't follow the VNAV path on descent any more in the same route it did before. It's a lot more slipperyTruth is it's a bit heavy at 125K pounds at T/D (FL230), but it was able to descend on VNAV no problem before installing the hot fix with the same config. Shouldn't VNAV calculate an earlier T/D instead of overshooting all of the altitude restrictions?Anyone with the same "issue"?

[NGX 1]

Dazz, Are you starting the decent exactly where the VNAV profile marks as the TOD or before/after?

[Robert Greene 2]

I havent installed any hotfixes yet, but Im going to right after I meet the crete in MSY. I will let you know If I get it too on my next leg.

[dazz 69]

Dazz, Are you starting the decent exactly where the VNAV profile marks as the TOD or before/after?

yeah, sure. VNAV all the way. just dialed the first altitude restriction of the STAR in the MCP and let it go down at T/D

I havent installed any hotfixes yet, but Im going to right after I meet the crete in MSY. I will let you know If I get it too on my next leg.

Thanks Bob I just tried a lower cruise altitude at FL210 and still the same. The FMC calculated a T/D some 5 - 10 miles later than with FL230 and ended with a "descent path unachievable" message after a while

[NGX 1]

Those messages pop up in the FMC when it can't calculate a vnav path to the destination. Is the route from TOD to airfield fluid? Ie no discontinuities?

[dazz 69]

Those messages pop up in the FMC when it can't calculate a vnav path to the destination. Is the route from TOD to airfield fluid? Ie no discontinuities?

yes, it's the same route I was flying before, no problem: LEAL MITO2A BRUNO IZA ILS06L LEPA It just can't follow the calculated descent in VNAV PATH cause it overspeeds and VNAV SPEED kicks in all the time.

[NGX 1]

Hmm. Strange indeed. You filed a support ticket? Topics are getting hidden quickly here.

[dazz 69]

Hmm. Strange indeed. You filed a support ticket? Topics are getting hidden quickly here.

No ticket yet. I'm probably missing something here. I'll try a different route, with a different setup. I guess if no one has posted with the same issue then it has to be something in my end and not a bug

[dazz 69]

Ok, tried with the 800WL, with the 900 w & w/o WL... 1% payload and 5K pounds of fuel, cost index 20 & 90. Same resultTried reinstalling everything too. can someone please confirm that the aircraft.cfg are supposed to be replaced by the hotfix 3? mine were not, so maybe there's my problem...

[mcbellette 145]

I know this isn't a helpful post, but just so everyone knows, I am not installing any hotfixes. My NGX works just fine from the base installer, so until a well-tested service pack is released, I'm going to wait on updating my NGX.

[dazz 69]

I know this isn't a helpful post, but just so everyone knows, I am not installing any hotfixes. My NGX works just fine from the base installer, so until a well-tested service pack is released, I'm going to wait on updating my NGX.

Yes, that's probably a good idea Matthew